Spontaneous allelic variant in deafness–blindness gene Ush1g resulting in an expanded phenotype

Relationships between novel phenotypic behaviors and specific genetic alterations are often discovered using target-specific, directed mutagenesis or phenotypic selection following chemical mutagenesis. An alternative approach is to exploit deficiencies in DNA repair pathways that maintain genetic integrity in response to spontaneously induced damage. Mice deficient in the DNA glycosylase NEIL1 show elevated spontaneous mutations, which arise from translesion DNA synthesis past oxidatively induced base damage. Several litters of Neil1 knockout mice included animals that were distinguished by their backwards-walking behavior in open-field environments, while maintaining frantic forward movements in their home cage environment. Other phenotypic manifestations included swim test failures, head tilting and circling. Mapping of the mutation that conferred these behaviors showed the introduction of a stop codon at amino acid 4 of the Ush1g gene. Ush1g^bw/bw null mice displayed auditory and vestibular defects that are commonly seen with mutations affecting inner-ear hair-cell function, including a complete lack of auditory brainstem responses and vestibular-evoked potentials. As in other Usher syndrome type I mutant mouse lines, hair cell phenotypes included disorganized and split hair bundles, as well as altered distribution of proteins for stereocilia that localize to the tips of row 1 or row 2. Disruption to the bundle and kinocilium displacement suggested that USH1G is essential for forming the hair cell's kinocilial links. Consistent with other Usher type 1 models, Ush1g^bw/bw mice had no substantial retinal degeneration compared with Ush1g^bw/+ controls. In contrast to previously described Ush1g alleles, this new allele provides the first knockout model for this gene.     

Phosphorus limitation of forest leaf area and net primary production on a highly weathered soil

We tested the hypothesis that P was the nutrient limiting net primary production of a nativeMetrosideros polymorpha forest on a highly weathered montane tropical soil in Hawaii. A factorial experiment used all combinations of three fertilizer treatments: nitrogen (N), phosphorus (P) and a mix of other essential nutrients (OE), consisting primarily of mineral derived cations and excluding N and P. P addition, but not N or OE, increased leaf area index within 12 months, foliar P concentration measured at 18 months, and stem diameter increment within 18 months. Stem growth at 18 months was even greater when trees fertilized with P also received the OE treatment. N and P additions increased leaf litterfall and N and P in combination further increased litterfall. The sequence of responses suggests that increased available P promoted an increase in photosynthetic area which led to increased wood production. P was the essential element most limiting to primary production on old volcanic soil in contrast to the N limitation found on young volcanic soils.     

Effects of chemical composition on nitrogen mineralization from green manures of seven tropical leguminous trees

Green manures from seven tropical leguminous trees were incubated with soil to determine the rates and controls of net nitrogen release. Fresh green manure (leaves and succulent twigs) was mixed with moist soil and incubated in polyethylene bags. Net N mineralization from green manures was estimated by the accumulation of extractable ammonium and nitrate minus the accumulation in soil alone. Patterns of N mineralization were complex, differed among species, and at 12 weeks ranged from 10 to 65 percent of original green-manure N. Cumulative net N mineralization was negatively correlated with initial soluble polyphenol content in the early phases of decomposition (1 through 8 weeks) and with initial lignin content in later phases (4 through 12 weeks). Neither initial percent N nor lignin: N ratio were strongly correlated with N mineralization. The best chemical index of N release was the initial polyphenol: N ratio. This study confirms previous findings that N mineralization from tropical legumes is controlled more by soluble polyphenols than by lignin or N content.     

Biomechanics of chelipeds in some decapod crustaceans

The major chelipeds of five species of decapod crustaceans were studied with reference to lever system mechanical advantage, pattern of occlusive geometry, and force/pressure developed during cheliped closure by intact animals. Every cheliped type was found to possess a linear array of two to four distinctive regions of occlusion. The factors responsible for the differences in occlusive design are discussed. It is suggested that crustacean major chelipeds must be regarded as regionally-specialized, multifunctional appendages.     

NMR characterization of copper and lipid interactions of the C2B domain of synaptotagmin I—relevance to the non-classical secretion of the human acidic fibroblast growth factor (hFGF-1)

Human fibroblast growth factor (hFGF-1) is a ∼ 17 kDa heparin binding cytokine. It lacks the conventional hydrophobic N-terminal signal sequence and is secreted through non-classical secretion routes. Under stress, hFGF-1 is released as a multiprotein complex consisting of hFGF-1, S100A13 (a calcium binding protein), and p40 synaptotagmin (Syt1). Copper (Cu²⁺) is shown to be required for the formation of the multiprotein hFGF-1 release complex (Landriscina et al. ,2001; Di Serio et al., 2008). Syt1, containing the lipid binding C2B domain, is believed to play an important role in the eventual export of the hFGF-1 across the lipid bilayer. In this study, we characterize Cu²⁺ and lipid interactions of the C2B domain of Syt1 using multidimensional NMR spectroscopy. The results highlight how Cu²⁺ appears to stabilize the protein bound to pS vesicles. Cu²⁺ and lipid binding interface mapped using 2D ¹H-¹⁵N heteronuclear single quantum coherence experiments reveal that residues in β-strand I contributes to the unique Cu²⁺ binding site in the C2B domain. In the absence of metal ions, residues located in Loop II and β-strand IV contribute to binding to unilamelar pS vesicles. In the presence of Cu²⁺, additional residues located in Loops I and III appear to stabilize the protein-lipid interactions. The results of this study provide valuable information towards understanding the molecular mechanism of the Cu²⁺-induced non-classical secretion of hFGF-1.     

Findings from the Peutz-Jeghers Syndrome Registry of Uruguay

Background

Peutz-Jeghers syndrome (PJS) is characterized by intestinal polyposis, mucocutaneous pigmentation and an increased cancer risk, usually caused by mutations of the STK11 gene. This study collected epidemiological, clinical and genetic data from all Uruguayan PJS patients.

Methods

Clinical data were obtained from public and private medical centers and updated annually. Sequencing of the STK11 gene in one member of each family was performed.

Results and discussion

25 cases in 11 unrelated families were registered (15 males, 10 females). The average age of diagnosis and death was 18 and 41 years respectively. All patients had characteristic PJS pigmentation and gastrointestinal polyps. 72% required urgent surgery due to intestinal obstruction. 3 families had multiple cases of seizure disorder, representing 20% of cases. 28% developed cancer and two patients had more than one cancer. An STK11 mutation was found in 8 of the 9 families analyzed. A unique M136K missense mutation was noted in one family. Comparing annual live births and PJS birth records from 1970 to 2009 yielded an incidence of 1 in 155,000.

Conclusion

The Uruguayan Registry for Peutz-Jeghers patients showed a high chance of emergent surgery, epilepsy, cancer and shortened life expectancy. The M136K missense mutation is a newly reported STK 11 mutation.     

Evolution of larval segment position across 12 Drosophila species*

Many developmental traits that are critical to the survival of the organism are also robust. These robust traits are resistant to phenotypic change in the face of variation. This presents a challenge to evolution. In this article, we asked whether and how a well-established robust trait, Drosophila segment patterning, changed over the evolutionary history of the genus. We compared segment position scaled to body length at the first-instar larval stage among 12 Drosophila species. We found that relative segment position has changed many times across the phylogeny. Changes were frequent, but primarily small in magnitude. Phylogenetic analysis demonstrated that rates of change in segment position are variable along the Drosophila phylogenetic tree, and that these changes can occur in short evolutionary timescales. Correlation between position shifts of segments decreased as the distance between two segments increased, suggesting local control of segment position. The posterior-most abdominal segment showed the highest magnitude of change on average, had the highest rate of evolution between species, and appeared to be evolving more independently as compared to the rest of the segments. This segment was exceptionally elongated in the cactophilic species in our dataset, raising questions as to whether this change may be adaptive.     

Short-Term Effects of Traditional and Alternative Community Interventions to Address Food Insecurity

Background

Despite the effects of food insecurity on health are well documented, clear governmental policies to face food insecurity do not exist in western countries. In Canada, interventions to face food insecurity are developed at the community level and can be categorized into two basic strategies: those providing an immediate response to the need for food, defined “traditional” and those targeting the improvement of participants’ social cohesion, capabilities and management of their own nutrition, defined “alternative”.

Objective

The objective of this study was to evaluate the effects of food insecurity interventions on food security status and perceived health of participants.

Design

This was a longitudinal multilevel study implemented in Montreal, Quebec, Canada. Participants were recruited in a two-stage cluster sampling frame. Clustering units were community organizations working on food insecurity; units of analysis were participants in community food security interventions. A total of 450 participants were interviewed at the beginning and after 9 months of participation in traditional or alternative food security interventions. Food security and perceived health were investigated as dependent variables. Differences overtime were assessed through multilevel regression models.

Results

Participants in traditional interventions lowered their food insecurity at follow-up. Decreases among participants in alternative interventions were not statistically significant. Participants in traditional interventions also improved physical (B coefficient 3.00, CI 95% 0.42–5.59) and mental health (B coefficient 6.25, CI 95% 4.15–8.35).

Conclusions

Our results challenge the widely held view suggesting the ineffectiveness of traditional interventions in the short term. Although effects may be intervention-dependent, food banks decreased food insecurity and, in so doing, positively affected perceived health. Although study findings demonstrate that food banks offer short term reprise from the effects of food insecurity, the question as to whether food banks are the most appropriate solution to food insecurity still needs to be addressed.     

Chronic Collection of Cerebrospinal Fluid from Rhesus Macaques (Macaca mulatta) with Cisterna Magna Ports: Update on Refinements

More than 20 y ago, we developed an animal model for chronic and continuous collection of cerebrospinal fluid (CSF) from conscious rhesus macaques. Since our previous publication in 2003, we have successfully implanted 168 rhesus macaques using this approach. Our experience enables us to provide up-to-date information regarding the model, including refinements to our implant design, reductions in maintenance, and new procedures for dealing with contamination. The results of our experiences have reduced the number of surgeries required and helped to increase the longevity of the implant, with some functioning for more than 18 y. Building on our success in rhesus macaques, we attempted to develop similar animal models in the African green monkeys and dogs but have been unable to develop reliable chronic models for CSF collection in these species.Abbreviation: CMP, cisterna magna port; CSF, cerebrospinal fluid

Cerebrospinal (CSF) biomarkers and pharmacokinetics are reliable tools for monitoring the therapeutic effect of compounds used for the treatment of various neurodegenerative diseases. CSF can be collected by using several methods, including lumbar and cisterna magna punctures or implanted devices.^{3,6,8,9,11-13} Each method has its own specific challenges but no matter which technique is used, performing CSF collections safely is imperative to avoiding risks to the animals and to providing the best CSF samples for analysis.¹ To support our research focus on neurocognitive disorders (including Alzheimer disease, Parkinson disease, and sleep disorders), we developed an NHP model of chronic CSF collection (the cisterna magna port [CMP] model) more than 20 y ago.⁴ This model allows safe, repeatable and reliable collections of CSF samples from the cisterna magna in conscious rhesus macaques (Macaca mulatta). The information summarized herein updates this animal model since its introduction in 2003 and reflects our 18 additional years of experience with it. We also provide information regarding our attempts to develop CMP models in African green monkeys and dogs. We recommend that readers review the 2003 article for further information and understanding of the CMP model.⁴